Glaucoma is a condition of the eye characterized by increased intraocular pressure. Untreated, the condition can eventually lead to irreversible retinal damage and blindness. Conventional therapy for glaucoma has involved topical administration of pilocarpine and/or epinephrine, and more recently beta-blockers, such as Timolol, administered to the eye several times daily.
Various beta-blocking agents may also be used to lower intraocular pressure. Such use is described, for example, in reviews by W. P. Boger in Drugs, 18, 25-32 (1979) and by T. J. Zimmerman and W. P. Boger in Survey Ophthalmol. 23(b), 347 (1979). The use of beta-blockers for the treatment of glaucoma is also described in the patent literature. For example, U.S. Pat. No. 4,195,085 to Stone discloses a method for treatment of glucoma by the ocular administration of a beta-blocking compound, timolol maleate. However, these methods also possess significant drawbacks, in that the absorption of the beta-blocking compound into the systemic circulation can cauase undesirable life-threatening side effects. Such side effects result from prolonged beta-blocking action on the heart, bronchioles and blood vessels. Accordingly, there is a need for compounds and a method of treatment of glucoma or for lowering intraocular pressure which is relatively free of unwanted systemic side effects.
Certain beta-blocking agents which contain enzymatically labile ester groups are known to exhibit short-acting beta-blocking effects in the systemic circulation. Such short-acting beta-blocking compounds (SAABs) have been suggested for treatment or prophylaxis of cardiac disorders as a means for reducing heart work or improving rhythmicity for a short duration. Such short-acting beta-blocking compounds avoid the sometimes counterproductive effects of conventional beta-blocking agents, whose effects are long-lived and, therefore, difficult to precisely control. Beta-blocking agents having such properties are described in U.S. Pat. Nos. 4,402,974, Sept. 6, 1983; 4,454,154, June 12, 1984; and 4,455,317, June 19, 1984.